Pesticides are transported through all media—soil, air, water, animals—and, as a result, can directly affect organisms all over the world. Political boundaries do not deter the movement of pesticides; thus, the ban of a chemical in one nation will not prevent the pesticide from traveling across national or political borders. As certain pesticides pass through the food chain, higher concentrations of the chemicals can accumulate at each successive level, thereby magnifying the dosage that higher trophic organisms uptake (for more information, see EPA’s PBT Fact Sheet).
Today, a number of different national and international agencies establish guidelines for directed uses of pesticides in order to mitigate potential harm to living organisms (see, e.g., U.S. EPA regulations FIFRA and TSCA, Health Canada’s Pesticide and Pest Management page, or the European Union’s REACH Program).
Of particular importance for this module is the Stockholm Convention on Persistent Organic Pollutants, an international treaty that aims to reduce or eliminate persistent organic pollutants in the environment (POPs). Administered by the United Nations Environment Programme, the convention was signed in 2001, went into force in 2004, and as of October 2011, the convention had 176 Parties (signatory nations). The convention initially identified 12 POPs (the “dirty dozen”, including DDT) and added an additional 10 through amendments to the convention in subsequent years. Each POP is listed in one or more category:
Annex A (Elimination): Parties must take measures to eliminate the production and use of the chemicals, with specific exemptions.
Annex B (Restriction): Parties must take measures to restrict the production and use of the chemicals in light of applicable acceptable purposes and/or specific exemptions.
Annex C (Unintentional production): Parties must take measures to reduce the unintentional releases of chemicals with the goal of continuing minimization and, where feasible, ultimate elimination.